Refractive Diopter Research Articles

Peripapillary retinal thickness and its risk factors in dry-type high myopia

IntroductionTo evaluate the alterations in the peripapillary retinal thickness and its risk factors in dry-type high myopia (HM). MethodsOne hundred and twenty eyes in 69 HM subjects were collected from March 2023 to July 2023 with the age, refractive diopter, axial length (AL), posterior scleral staphyloma, type of myopic maculopathy, and peripapillary retinal thickness. Divided into three groups according to the international photo-graphic classification system: Category 0 (C0) with no myopic retinal degenerative lesions, Category 1 (C1) with tessellated fundus, and Category 2 (C2) with diffuse chorioretinal atrophy. Peripapillary retinal thickness was assessed using swept-source optical coherence tomography (SS-OCT) B-scans. All data were analyzed with the SPSS software version 23.0 by one-way ANOVA test among three groups. Linear regression and pearson correlation analysis were used to determine the relationships among measurements. ResultsThe retinal thickness of the peripapillary was measured from the superior, nasal, inferior, and temporal directions around the optic disc. The superior, nasal, and inferior peripapillary retinal thickness in the C2 group decreased significantly in all three groups. The retinal thicknesses decreased significantly with the increase of AL in the superior, nasal, and inferior. The retinal thicknesses increased significantly with the increase of refractive diopter, except for the temporal sector. The retinal thickness decreased significantly with the increase of age in dry-type HM. There was no significant difference between peripapillary retinal thickness and the wide macular staphyloma. ConclusionsIndividuals in the C2 group had a thinner peripapillary retinal thickness than other groups, except for the temporal sector. The retinal thicknesses of the peripapillary decreased significantly with the increase of AL and increased significantly with the increase of refractive diopter, except for the temporal sector. With the increase of age, the retinal thickness of the peripapillary decreased significantly. Ophthalmologists and HM patients should pay attention to changes in the thickness of the peripapillary retina and the growth of age.

Comparison of Different Intraocular Lens Power Calculation Formulas in Eyes With Primary Angle Closure.

Prospective case series. This prospective study determines which formulas can best predict the refractive outcome in patients with primary angle closure disease (PACD) after cataract surgery. To compare the accuracy of 6 intraocular lens power calculation formulas, Barrett Universal II (BU II), Haigis, Hoffer Q, Holladay I, Kane and SRK/T, in eyes with PACD. Patients diagnosed with PACD and cataracts and who met the indication for cataract surgery were enrolled in the study. Six intraocular lens power calculation formulas were used to calculate the refractive diopter. The percentage of eyes with prediction error (PE) within ±0.50 D and the median absolute PE were compared to determine the accuracy of different formulas in patients with PACD. Subgroup analysis was performed according to axial length (AL). The accuracy of BU II was compared between patients with PACD and patients with age-related cataracts. One hundred five patients (105 eyes) with PACD and 35 patients (35 eyes) with age-related cataracts were enrolled in the study. Haigis, Kane, and BU II formula achieved a comparable outcome and outperformed over the other 3 formulas in patients with PACD. Subgroup analysis showed that the group with long AL has lower values of median absolute PE. PE was significantly positively correlated with AL and negatively correlated with relative lens position when calculated using BU II and Kane. Haigis, Kane, and BU II formula achieved a comparable outcome and outperformed over the other 3 formulas in patients with PACD.

Efficacy of scleral buckling for the treatment of rhegmatogenous retinal detachment using a novel foldable capsular buckle.

To evaluate the effectiveness and safety of scleral buckling for the treatment of rhegmatogenous retinal detachment (RRD) using a novel foldable capsular buckle (FCB). This was a series of case observation studies. Eighteen patients (18 eyes) who visited our ophthalmology department between August 2020 and August 2022 and were treated for RRD with scleral buckling using FCB were included. The procedure was similar to conventional scleral buckling, while a balloon-like FCB was placed onto the retinal break with balanced salt solution filling for a broad, external indentation instead of the silicone buckle. The retinal reattachment rate, best corrected visual acuity (BCVA), intraocular pressure (IOP), refractive dioptre and astigmatism degree, and complications were evaluated and recorded. There were 7 males and 11 females aged 19-58y. The average time course of RRD was 12d, ranging from 7-20d. The retinal break was located in the superior quadrants in 8 eyes and in the inferior quadrants in 10 eyes, with macula-off detachments in 12 eyes. The patients were followed-up for at least 6mo. The final retinal reattachment rate was 100%. The BCVA was significantly improved compared with the baseline (P<0.05). There was no significant change in refractive dioptre or astigmatism degree at each follow-up (all P>0.05). Three patients had transiently high IOPs within one week after surgery. Mild diplopia occurred in 5 patients after surgery and then disappeared after the balloon fluid was removed. The success rate of FCB scleral buckling for RRD is satisfactory. This procedure can be expected to be applied in new, uncomplicated cases of RRD.

Gut microbiome and plasma metabolome alterations in myopic mice.

Myopia is one of the most common eye diseases leading to blurred distance vision. Inflammatory diseases could trigger or exacerbate myopic changes. Although gut microbiota bacteria are associated with various inflammatory diseases, little is known about its role in myopia. The mice were randomly divided into control and model groups, with the model group being attached-30D lens onto the eyes for 3 weeks. Then, mouse cecal contents and plasma were collected to analyze their intestinal microbiota and plasma metabolome. We identified that the microbial composition differed considerably between the myopic and non-myopic mice, with the relative abundance of Firmicutes phylum decreased obviously while that of Actinobacteria phylum was increased in myopia. Furthermore, Actinobacteria and Bifidobacterium were positively correlated with axial lengths (ALs) of eyeballs while negatively correlated with refractive diopters. Untargeted metabolomic analysis identified 141 differentially expressed metabolites, and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed considerable enrichment mainly in amino acid metabolism pathways. Notably, pathways involved glutamate metabolism including "Glutamine and D-glutamate metabolism" and "Alanine, aspartate and glutamate metabolism" was changed dramatically, which presented as the concentrations of L-Glutamate and L-Glutamine decreased obviously in myopia. Interestingly, microbiome dysbiosis and metabolites alternations in myopia have a disrupting gut barrier feature. We further demonstrated that the gut barrier function was impaired in myopic mice manifesting in decreased expression of Occludin, ZO-1 and increased permeation of FITC-dextran. Myopic mice had obviously altered gut microbiome and metabolites profiles compared to non-myopic mice. The dysbiosis and plasma metabolomics shift in myopia had an interrupting gut barrier feature. Our study provides new insights into the possible role of the gut microbiota in myopia and reinforces the potential feasibility of microbiome-based therapies in myopia.

Prospective evaluation of the ESCRS online calculator for calculation of a multifocal intraocular lens.

To evaluate a recently introduced ESCRS online calculator for intraocular lens (IOL) calculation of a multifocal IOL in refractive lens exchange and cataract surgery in a prospective setting. Department of Ophthalmology, Goethe University Frankfurt, Germany. Prospective, consecutive case series. We included eyes that received lens extraction and multifocal IOL implantation. We compared the mean prediction error (MPE), mean and median absolute prediction error (MAE, MedAE) of the online calculator provided by the European Society of Cataract and Refractive Surgeons (ESCRS), and number of eyes within ±0.5, ±1.0, ±2.0 diopters (D) of target refraction. Additionally, the SRK/T formula was included for comparison as well. Postoperative spherical equivalent was measured at 3 months. Only one eye per patient was included. Eighty-eight eyes from 88 patients with mean age of 62 years ± 9.5 were included. The MedAE was low for all formulas and ranged from 0.26D (Kane), Hill-RBF (0.27D), Hoffer QST (0.27D), Barrett (0.28D), EVO (0.29D), Cooke K6 (0.27D), 0.30D (Pearl DGS) to 0.31D (SRK/T). No statistically significant difference was found (p = 0.627). Considering the number of eyes within ±0.5D of the calculated refraction the best performing was again the Hill-RBF (84%, 74 eyes), again followed by Kane (71, 81%), EVO, Pearl DGS, Hoffer QST, Barrett (each 80%, 70 eyes),Cooke K6 (78%, 69 eyes), and SRK/T (74%). Again, no statistically significant difference was found (p = 0.39). Using recently introduced ESCRS online IOL calculator in multifocal intraocular lenses leads to a high number of eyes reaching target refraction and low prediction errors. All formulas performed similar well. However, Hill-RBF showed the highest number of eyes within ±0.5D, but no significance was found regarding this.

Neurovascular coupling dysfunction in high myopia patients: Evidence from a multi-modal magnetic resonance imaging analysis

Background and purposeTo investigate neurovascular coupling dysfunction in high myopia (HM) patients. Materials and methodsA total of 37 HM patients and 36 healthy controls were included in this study. Degree centrality (DC), regional homogeneity (ReHo), amplitude of low-frequency fluctuations (ALFF), and fractional ALFF (fALFF) maps were employed to represent neuronal activity. Cerebral blood perfusion was characterized by cerebral blood flow (CBF). The correlation coefficient was calculated to reflect the relationship between neuronal activity and cerebral blood perfusion. Pearson partial correlation analysis was utilized to evaluate the association between HM dysfunction and clinical indicators. ResultsHM patients exhibited significant alterations in neurovascular coupling across 37 brain regions compared to healthy controls. The brain regions with marked changes varied among the four neurovascular coupling patterns, including the middle frontal gyrus, superior occipital gyrus, middle occipital gyrus, and fusiform gyrus. Additionally, the superior frontal gyrus orbital part, medial superior frontal gyrus, inferior occipital gyrus, and dorsolateral superior frontal gyrus displayed significant changes in three coupling patterns. In HM patients, the ReHo-CBF changes in the inferior frontal gyrus orbital part were positively correlated with best-corrected visual acuity (BCVA) and refractive diopter changes. Similarly, the ALFF-CBF changes in the inferior frontal gyrus orbital part showed a positive correlation with refractive diopter changes. ReHo-CBF and ALFF-CBF alterations in the paracentral lobule were positively correlated with BCVA and refractive diopter changes. ConclusionOur findings underscore the abnormal alterations in neurovascular coupling across multiple brain regions in HM patients. These results suggest that neurovascular dysfunction in HM patients may be associated with an aberrant visual regulation mechanism.

Microvasculature and microstructure alteration in dry-type high myopia.

To investigate the alterations in the retinal vasculature and microstructure in dry-type high myopia. One hundred and eighty-nine dry-type high myopia eyes were classified into three groups. Group 1 consisted of 86 eyes with no myopic retinal degenerative lesion (C0). Group 2 consisted of 71 eyes with tessellated fundus (C1). Group 3 consisted of 32 eyes with diffuse chorioretinal atrophy (C2). Retinal vascular density and retinal thickness were measured with optical coherence tomography angiography. The scanning area was a 3 × 3 mm2 ring with the fovea of the macular. All data were analyzed with the SPSS 23.0 by one-way ANOVA test among comparison groups. Pearson's correlation analysis was used to determine the relations among measurements. Univariate linear regression showed a correlation between the vascular densities and retinal thicknesses. The microvessel density significantly decreased and significant thinning of the superior and temporal macular thickness in the C2 group. The vascular densities of macular decreased significantly with the increase of axial length (AL) and refractive diopter in the C2 group. The retinal thicknesses of the macular fovea increased significantly with the increase of vascular densities in the C0 group and C1 group. The impairment of retinal microstructure is more likely related to reduced oxygen and nutrients due to microvessel density decreases.

Photobiomodulation therapy retarded axial length growth in children with myopia: evidence from a 12-month randomized controlled trial evidence

To determine whether photobiomodulation (PBM) therapy can retard ocular axial length (AL) in children with myopia. A randomized controlled clinical trial was conducted on two consecutive cohorts of 50 eligible children aged 8–12 years with ≤ − 0.75 Diopter (D) of spherical equivalent refraction (SER). Participants were randomly assigned to the intervention group (n = 25) and treated with PBM therapy or the control group (n = 25) and treated with single vision spectacles only. At the 12-month follow-up, the changes in AL and cycloplegic SER from baseline were both compared between the two groups. In addition, the subfoveal choroidal thickness (SFChT), anterior chamber depth (ACD), and central corneal refractive power (CCP) were analysed at the 3-, 6-, 9-, and 12-month follow-ups, respectively. Among the 50 children, 78% were included at the final follow-up, with a mean age of 9.7 ± 1.5 years and a mean SER of − 2.56 ± 1.70. The mean difference in AL growth between the two groups at 12 months was 0.50 mm (PBM vs. Control, − 0.02 mm ± 0.11 vs. 0.48 mm ± 0.16, P < 0.001), and the mean difference in cycloplegic SER at 12 months was + 1.25 D (PBM vs. Control, + 0.28 D ± 0.26 vs. − 0.97 D ± 0.25, P < 0.001). There were no significant differences in any of the other parameters (including SFChT, ACD, and CCP) between the two groups at any time point. PBM therapy is an effective intervention for slightly decreasing the AL to control myopia in children.Trial registration: Chinese Clinical Trial Registration Number: ChiCTR2100043619. Registered on 23/02/2021; prospectively registered. http://www.chictr.org.cn/showproj.aspx?proj=121302.

Changes of the effective optical zone after small-incision lenticule extraction and a correlation analysis.

The objective of the study is to observe the changes in the effective optical zone (EOZ) after small incision lenticule extraction (SMILE) and explore possible correlations with some influencing factors. In total, 133 eyes after SMILE were divided into the mild to moderate myopia group (- 1.75 D to - 5.75 D, 70 eyes) and the high myopia group (- 6.00 D to - 9.50 D, 63 eyes). The postoperative EOZ was calculated by utilizing the corneal tangential curvature map. Changes in EOZ (△-OZ) were monitored and compared between the two groups. Pearson correlation analysis was conducted to determine the correlation between △-OZ and corneal high-order wavefront aberrations. Multicollinearity analysis and ridge regression analysis were performed to assess the correlation between △-OZ and some corneal parameters. After SMILE, the horizontal EOZ (H-EOZ), vertical EOZ (V-EOZ), and average EOZ (A-EOZ) were significantly smaller than the programmed optical zone (POZ) in both groups (p < 0.05). The difference between V-EOZ and POZ (△V-OZ) and the difference between A-EOZ and POZ (△A-OZ) showed more significant changes in the high myopia group than in the mild to moderate myopia group, and △V-OZ was significantly larger than the difference between H-EOZ and POZ (△H-OZ) in the high myopia group. In both groups, the total high-order aberration (T-HOA) and spherical aberration (SA) both increased after SMILE, and they had a similar significant negative correlation with A-EOZ. Moreover, there was a significant negative correlation between △-OZ and Km (X1), Q-value (X2), spherical equivalent (SE, X3), ablating depth (AD, X4) and △e (X6), and a significant positive correlation between △-OZ and △Q (X5). △H-OZ was expressed as Y1, △V-OZ as Y2, and △A-OZ as Y3. The multiple linear regression equations were as follows: Y1 = 3.683 - 0.065X1, Y2 = 1.549 - 0.469X2 - 0.059X3, Y3 = 4.015 - 0.07X1 - 0.03X3, Y1 = 1.337 - 0.005X4 + 0.413X5, Y2 = 1.265 + 0.469X5, and Y3 = 0.852 - 0.002X4 - 0.398X6. The correlation degree with △A-OZ was ranked as Km > △Q > Q-value > AD > e-value > △e > SE > △Km, as represented by the ridge regression analysis. The EOZ was irregularly reduced after SMILE, which should be taken into consideration in the design of POZ, especially for high myopia. Consideration of the refractive diopter and corneal topography is advised for the design of POZ, the latter of which has greater reference significance.

Predictive Accuracy of the Hill-RBF 2.0 Formula in Pediatric Eyes: Comparison of 5 Intraocular Lens Formulas.

To compare the predictive accuracy of the Hill-Radial Basis Function (Hill-RBF) 2.0 formula with the Barrett Universal II, Hoffer Q, SRK/T, and Holladay 1 formulas in pediatric eyes. In this observational study, 99 eyes of 70 children 4 to 18 years old with clinically significant congenital or developmental cataracts attending the pediatric ophthalmology clinic in Guru Nanak Eye Centre were included. Optical biometry was performed in all patients with the Lenstar LS-900 (Haag-Streit). Intraocular lens (IOL) power predicted by the Hill-RBF formula was selected. Mean absolute prediction error (MAE) at 8 weeks of follow-up was calculated for the Hill-RBF, Barrett Universal II, Hoffer Q, SRK/T, and Holladay 1 IOL power formulas. Percentages of eyes having residual refraction within ±0.50, ±0.50 to ±1.00, and greater than ±1.00 diopters (D) of target refraction were calculated. The MAEs were 1.08 ± 1.00 D for the Hill-RBF, 1.24 ± 1.20 D for the Barrett Universal II, 1.25 ± 1.06 D for the Hoffer Q, 1.25 ± 1.10 D for the SRK/T, and 1.28 ± 1.01 D for the Holladay 1 formulas. The Hill-RBF formula had the lowest MAE, which was significantly lower than the Holladay 1 and Hoffer Q formulas. However, the difference in MAE between the Hill-RBF and the SRK/T and Barrett Universal II formulas was not statistically significant (P > .05). The Hill-RBF group had the maximum percentage of eyes with residual error within ±0.50 D of the target refraction. The overall evidence from the studies indicates that the Hill-RBF method that uses artificial intelligence and works independent of specific anatomical features is non-inferior to the Barrett Universal II, Hoffer Q, SRK/T, and Holladay 1 formulas in pediatric eyes. [J Pediatr Ophthalmol Strabismus. 2023;60(4):282-287.].

Effectiveness of Laser Refractive Surgery to Address Anisometropic Amblyogenic Refractive Error in Children: A Report by the American Academy of Ophthalmology

To review the published literature assessing the safety and effectiveness of laser refractive surgery to treat anisometropic amblyogenic refractive error in children aged ≤ 18 years. A literature search of the PubMed database was conducted in October 2021 with no date limitations and restricted to publications in English. The search yielded 137 articles, 69 of which were reviewed in full text. Eleven articles met the criteria for inclusion and were assigned a level of evidence rating. The 11 included articles were all level III evidence and consisted of 1 case-control study and 10 case series. Six studies used laser-assisted in situ keratomileusis (LASIK), 1 used photorefractive keratectomy (PRK), 1 used refractive lenticule extraction/small incision lenticule extraction, and the rest used a combination of LASIK, PRK, laser epithelial keratomileusis (LASEK), or refractive lenticule extraction/small incision lenticule extraction. Five studies enrolled patients with anisometropic myopia, 2 studies enrolled patients with anisometropic hyperopia, and the remainder were mixed. Although all studies demonstrated an improvement in best-corrected visual acuity (BCVA), the magnitude of improvement varied widely. As study parameters varied, a successful outcome was defined as residual refractive error of 1 diopter (D) or less of the target refraction because this was the most commonly used metric. Successful outcomes ranged between 38% and 87%, with a mean follow-up ranging from 4 months to 7 years. Despite this wide range, all studies demonstrated an improvement in the magnitude of anisometropia. Regression in refractive error occurred more frequently and to a greater degree in myopic eyes and eyes with longer follow-up, and in younger patients. Although one study reported 2 free flaps, most studies reported no serious adverse events. The most common complications were corneal haze and striae. Findings from included studies suggest that laser refractive surgery may address amblyogenic refractive error in children and that it appears to decrease anisometropia. However, the evidence for improvement in amblyopia is unclear and long-term safety data are lacking. Long-term data and well-designed clinical studies that use newer refractive technologies in standardized patient populations would help address the role of refractive surgery in children and its potential impact on amblyopia.

Visual differences in topography-guided versus wavefront-optimized LASIK in the treatment of myopia: a Meta-analysis.

To investigate the potential differences between topography-guided (TG) and wavefront-optimized (WFO) laser in situ keratomileusis (LASIK) for the treatment of myopia. A systematic literature search was performed to determine relevant trials comparing LASIK with TG and WFO from the time of library construction to August 2020, and The PubMed, Cochrane, Web of Science, EMBASE and Chinese databases (i.e. CNKI, CBM, WAN FANG and VIP) were accessed. The data on visual acuity, refractive status and wavefront aberration were retrieved and evaluated from three to six months after surgery. STATA (version 14.0) software was used for statistical analysis. A cumulative Meta-analysis was simultaneously performed. Eleven studies with a total of 1425 eyes were incorporated. No statistically significant differences were evident between TG and WFO ablation in the proportion of eyes achieving an uncorrected distance visual acuity (UCVA) of 20/20 or better (P=0.377), gaining one line or more (P=0.05), postoperative cylinder (P=0.40), vertical coma (P=0.593) and horizontal coma (P=0.957). After TG ablation, the proportion of the patients' eyes of which postoperative refraction is within ±0.5 diopter of the target refraction was significantly higher than that undergoes WFO (P=0.003). As opposed to the WFO group, manifest refraction spherical equivalent (MRSE; P=0.000) was lower, and UCVA (P=0.005) was better in the TG group. The higher-order aberrations (HOAs; P=0.000), spherical aberration (P=0.000) and coma (P=0.000) were significantly lower in TG group. The cumulative Meta-analysis illustrated that the proportion of eyes achieving UCVA of 20/20 or better, postoperative refraction within ±0.5 diopter, and MRSE has steady between the two groups. Both TG-LASIK and WFO-LASIK are safe, effective, and predictable for correcting myopia. TG-LASIK may produce fewer aberration and is more precise than WFO-LASIK.

Long-term Outcomes of Cataract Surgery in Patients With Chronic Ocular Graft-Versus-Host Disease.

The aim of this study was to evaluate the outcomes of cataract surgery in patients with chronic ocular graft-versus-host disease (GVHD). A retrospective review was performed on 77 eyes of 42 patients with chronic ocular GVHD that underwent cataract surgery between January 2014 and February 2020 in a tertiary institution. Posterior subcapsular cataract was seen in 53 (68.8%) of 77 eyes, with a mean preoperative corrected distance visual acuity (CDVA) of 0.61 ± 0.49 logarithm of the minimum angle of resolution (logMAR). Postoperatively, with a mean follow-up of 21 months, CDVA improved to 0.17 ± 0.22 logMAR at the latest visit (P < 0.0001). With latest available refraction, 42 (57.5%) of 73 eyes were within 0.5 diopters of target refraction, and 59 eyes (80.8%) were within 1.0 diopter. Postoperative complications included superficial punctate keratopathy within 1 month postoperatively (19 eyes, 24.7%), posterior capsular opacification requiring yttrium-aluminum-garnet (YAG) laser capsulotomy (36 eyes, 46.8%), corneal epithelial defect (7 eyes, 9.1%), filamentary keratopathy (5 eyes, 6.5%), cystoid macular edema (3 eyes, 3.9%), and infectious crystalline keratopathy (1 eye, 1.3%). Lower preoperative National Institutes of Health ocular GVHD severity scores were associated with a better postoperative CDVA (grade 1, 0.13 ± 0.16 logMAR; grade 2, 0.16 ± 0.23 logMAR; and grade 3, 0.36 ± 0.21 logMAR; P = 0.004). Cataract surgery improves visual acuity long term in most patients with chronic ocular GVHD. Close postoperative monitoring is important to detect ocular surface inflammation secondary to chronic ocular GVHD, particularly in severe ocular GVHD.

Comparison of Wavefront-Guided Femtosecond LASIK and Optimized SMILE for Correction of Moderate-to-High Astigmatism.

To compare refractive outcomes, higher order aberrations (HOAs), and the changes in contrast sensitivity after wavefront-guided femtosecond laser-assisted in situ keratomileusis (WFG LASIK) and optimized small incision lenticule extraction (SMILE) for moderate-to-high astigmatism correction. This prospective, randomized study included 87 eyes: 40 eyes in the WFG LASIK group and 47 eyes in the SMILE group. Manual cyclotorsion compensation by marking the horizontal axis before SMILE surgery was used for optimized SMILE. Refractive diopter, aberrations, and contrast sensitivity were assessed 3 months postoperatively. The Alpins vector analysis method was used to analyze the astigmatic changes after surgery. There were no significant differences in the corrected distance visual acuity and refraction between the two groups after surgery. The fitted curve of surgically induced astigmatism versus target induced astigmatism was described as y = 0.9905 x + 0.0009 in the WFG LASIK group and y = 0.9672 x + 0.0026 in the SMILE group. The percentage of corneal astigmatism axis change within 5 degrees was statistically significant (chi-square test: 10.632, P = .001). HOAs increased in both the WFG LASIK and SMILE groups after surgery (t = -3.655, P = .001, t = -3.784, P = .001, respectively). However, comparison of the changes of HOAs between both groups was not significant (t = -0.565, P = .575). The improvement in contrast sensitivity in the WFG LASIK group was significantly higher than that in the SMILE group. WFG LASIK and optimized SMILE can achieve similar outcomes for astigmatism correction. Optimized SMILE with marking could achieve good astigmatism correction, even without an eye tracking system. [J Refract Surg. 2021;37(3):166-173.].

Intraocular lens power calculation for plus and minus lenses in high myopia using partial coherence interferometry

PurposeWe assessed the accuracy of lens power calculation in highly myopic patients implanting plus and minus intraocular lenses (IOL).MethodsWe included 58 consecutive, myopic eyes with an axial length (AL) > 26.0 mm, undergoing phacoemulsification and IOL implantation following biometry using the IOLMaster 500. For lens power calculation, the Haigis formula was used in all cases. For comparison, refraction was back-calculated using the Barrett Universal II (Barrett), Holladay I, Hill-RBF (RBF) and SRK/T formulae.ResultsThe mean axial length was 30.17 ± 2.67 mm. Barrett (80%), Haigis (87%) and RBF (82%) showed comparable numbers of IOLs within 1 diopter (D) of target refraction. Visual acuity (BSCVA) improved (p < 0.001) from 0.60 ± 0.35 to 0.29 ± 0.29 logMAR (> 28-days postsurgery). The median absolute error (MedAE) of Barrett 0.49 D, Haigis 0.38, RBF 0.44 and SRK/T 0.44 did not differ. The MedAE of Haigis was significantly smaller than Holladay (0.75 D; p = 0.01). All median postoperative refractive errors (MedRE) differed significantly with the exception of Haigis to SRK/T (p = 0.6): Barrett − 0.33 D, Haigis 0.25, Holladay 0.63, RBF 0.04 and SRK/T 0.13. Barrett, Haigis, Holladay and RBF showed a tendency for higher MedAEs in their minus compared to plus IOLs, which only reached significance for SRK/T (p = 0.001). Barrett (p < 0.001) and RBF (p = 0.04) showed myopic, SRK/T (p = 002) a hyperopic shift in their minus IOLs.ConclusionsIn highly myopic patients, the accuracies of Barrett, Haigis and RBF were comparable with a tendency for higher MedAEs in minus IOLs. Barrett and RBF showed myopic, SRK/T a hyperopic shift in their minus IOLs.

Secondary Piggyback Intraocular Lens for Management of Residual Ametropia after Cataract Surgery

PurposeTo investigate the indications, clinical outcomes, and complications of secondary piggyback intraocular lens (IOL) implantation for correcting residual refractive error after cataract surgery.MethodsIn this prospective interventional case series, patients who had residual refractive error after cataract surgery and were candidates for secondary piggyback IOL implantation between June 2015 and September 2018 were included. All eyes underwent secondary IOL implantation with the piggyback technique in the ciliary sulcus. The types of IOLs included Sulcoflex and three-piece foldable acrylic lenses. Patients were followed-up for at least one year.ResultsEleven patients were included. Seven patients had hyperopic ametropia, and four patients had residual myopia after cataract surgery. The preoperative mean of absolute residual refractive error was 7.20 7.92, which reached 0.42 1.26 postoperatively (P 0.001). The postoperative spherical equivalent was within 1 diopter of target refraction in all patients. The average preoperative uncorrected distance visual acuity was 1.13 0.35 LogMAR, which significantly improved to 0.41 0.24 LogMAR postoperatively (P = 0.008). There were no intra- or postoperative complications during the 22.4 9.5 months of follow-up.ConclusionSecondary piggyback IOL implantation is an effective and safe technique for the correction of residual ametropia following cataract surgery. Three-piece IOLs can be safely placed as secondary piggyback IOLs in situations where specifically designed IOLs are not available.

Analysis of macular microvasculature and thickness after ICL implantation in patients with myopia using optical coherence tomography.

To investigate changes in macular vessels and thickness in myopic eyes after intraocular collamer lens (ICL) implantation using quantitative optical coherence tomography angiography (OCTA). This retrospective included 73 myopic eyes of 73 patients (average age, 27.53±6.16y) who underwent ICL implantation (28 eyes were Toric ICL). Axial length (AL), uncorrected visual acuity (UCVA), refractive dioptre (RD), intraocular pressure (IOP) and OCTA were measured and compared with before and 1wk, 1, and 3mo after surgery. OCTA was used to image vessel density (VD) and skeleton density (SD) in both the superficial (SCP) and deep capillary plexus (DCP). Central retinal thickness (CRT) and ganglion cell-inner plexiform layer thickness (GCT) were also measured. Changes between pre- and postoperative measurements were analysed by repeated measures analysis of variance. Compared with preoperative data, postoperative data on UCVA revealed significant improvements in all patients (P<0.05). However, there was no significant difference in IOP. After the operation, CRT and GCT exhibited significant changes (P<0.05). Among these measures, CRT was significantly higher at one and three months postoperative (all P<0.01). GCT was significantly higher at 1wk, 1, and 3mo postoperative (all P<0.01). Changes in VD and SD were nonsignificant in both the SCP and DCP. There was no difference in postoperative changes between the ICL and Toric ICL groups. ICL and Toric ICL implantation both have good efficacy and safety for myopic eyes, but macular area changes that occur after surgery need attention.

Wavefront excimer laser refractive surgery for adults with refractive errors.

Wavefront excimer laser refractive surgery for adults with refractive errors.

Refractive and Visual Outcomes after Scleral Fixated Intraocular Lens Implantation in Children with Ectopia Lentis

This study was conducted to report the refractive and visual outcome after Scleral Fixated Intraocular Lens (SFIOL) implantation in children with nontraumatic ectopia lentis. Retrospective review of the medical records of 25 eyes of 15 patients who underwent SFIOL implantation in children with non-traumatic ectopia lentis. The mean best corrected visual acuity (BCVA) before SFIOL implantation was 1.07 ± 0.9 logMar units [median: 0.9, Interquartile range (ΙQR): 0.415 to 1.555] which improved to 0.41 ± 0.33 logMar units (median: 0.22, ΙQR: 0.180 to 1.555) at two months postoperative follow up. In phakic group, the mean spherical refraction preoperatively was -12.04 ± 7.82 DS (dioptre sphere) (IQR: +16 to -5.875) and postoperatively was +0.93 ± 2.67DS (IQR: -0.375 to +2). In aphakic group, the mean spherical refraction preoperatively was +12.22 ± 2.05 DS and postoperatively was +1.2 ± 1.9 DS. The mean total astigmatism preoperatively was -6.44 ± 4.95 DC (dioptre cylinder) (median: 6, IQR: -10.50 to +2) and postoperatively was -1.47 ± 0.98 DC (median: -1.5, IQR: -2 to - 0.625 ). The mean IOL induced astigmatism was -1.01 ± 0.95 DC (median -0.75, IQR: -1.33 to - 0.25). The spherical refractive equivalent was within 2 Diopter (D) of the target refraction calculated preoperatively in 20 eyes and in five eyes it was more than 2 D. SFIOL implantation is associated with good visual outcome with a significant improvement in the refractive error. However, a longer follow up is required to assess the change of refraction and the stability of the SFIOL.

Clinical outcomes of corneal refractive surgery comparing centration on the corneal vertex with the pupil center: a meta-analysis.

To compare the visual and refractive outcomes between centration on the corneal vertex and the pupil center in corneal refractive surgery. A comprehensive literature search was conducted using PubMed, MEDLINE, EMBASE, and the Cochrane Library to identify relevant studies. The primary outcomes were the postoperative spherical equivalent (SE), effectiveness [uncorrected distance visual acuity (UDVA) ≥ 20/20, eyes within ± 0.50 diopter (D) of target refraction], and safety [loss ≥ 2 lines of corrected distance visual acuity (CDVA)]. Higher-order aberrations were considered secondary outcomes. Seven studies describing a total of 1964 eyes were included in this meta-analysis. A statistical significance in postoperative SE was found between the two centration methods for the correction of myopia that favor the CV-centered method (p < 0.001). No significant differences were observed in the proportion of eyes with UDVA ≥ 20/20 or loss ≥ 2 lines of CDVA postoperatively. However, the proportion of eyes within ± 0.50 D was slightly higher (p = 0.02) and the coma aberration was much lower in the corneal vertex-centered method (p < 0.001). Preferable visual and refractive outcomes could be achieved with either centering on the corneal vertex or pupil center in corneal refractive surgery; however, the corneal vertex-centered method has shown partial benefits in some clinical indices. In order to obtain higher quality of clinical evidences, more randomized controlled trials (RCTs) are required in further investigations.